INTRODUCTION 49 



hypothetical group of Monera. In the majority of Bacteria and 

 spirochetes and in more complex ciliate t^-pes Kke Dileptus a user, 

 Holosticha, etc., the functions which the cell nucleus are supposed 

 to perform are either absent altogether, or, which is more probable, 

 they are performed by the distributed chromidiosomes or chromidia. 



3. Volutin Grains.— These are widely distributed in Protozoa and 

 are difficult to distinguish from chromidiosomes. They are usuall\' 

 spherical in form and stain intensely with the basic d^^es, retaining 

 the stain even after the chromatin granules are completely extracted. 

 They were discovered by a pupil of A. Meyer in the cells of Spir- 

 ilhim volvtans from which the peculiar name is derived, and, accord- 

 ing to Guilliermond. they are identical with the "metachromatic 

 bodies" of Babes, and with the "red granules" discovered by 

 Biitschli. Meyer regarded them as composed largely of nucleic acid, 

 a conclusion supported b,y the experiments of Reichenow (1909) on 

 Hematococcus in which it was sho^m that volutin grains disappear 

 in a medium free from phosphorus and that, during the phases of 

 active chromatic increase in the nucleus, they diminish perceptibly 

 in size and increase in size when the chromatin content becomes 

 stationary. From these residts, confirmed by van Herwerden 

 (1917) on yeast cells, Reichenow concluded that ^'olutin grains play 

 a most important part in the vital activities of the cell and he 

 regards them as a reserve store of nucleo-proteins for the purpose 

 of chromatin gro^\th in the nucleus. They take a yellow stain with 

 iodine and a red stain with methylene blue and 1 per cent solution 

 of sulphuric acid, while their reaction to the usual chromatin stains 

 makes them difficult to distinguish from chromidia. They appear 

 to be formed in the cj'toplasm and, if these observations are well 

 foimded, are entirely different in origin and in function from the 

 other minute granules which they closely resemble. The import- 

 ance of these conclusions in problems connected with biology of 

 the cell warrants the demand for further and more complete obser- 

 vations and experiments. 



4. Chondriosomes (Mitochondria) — Chondriosomes appear to be 

 permanent granules in the cytoplasm of many types of Protozoa in 

 A\-hich the}' have been studied mainly by Faure-Fremiet, Vonwiller 

 (1918), and Cowdry (1918). Like other granules in the cyto- 

 plasm they are usually spherical and very minute (0.5 /^ to 1.5 ^ in 

 diameter), but imlike many other granules each appears to retain 

 its individuality from generation to generation b}- dividing prior 

 to or during division of the cell. 



Observations of the chondriosomes of Protozoa are too scanty to 

 permit of definite conclusions regarding their history or function 

 in the cell and their chemical composition is quite unknown. Faure- 

 Fremiet regards them as combinations of albumin with phosphates 

 or with fatty acids, and belie\'es that they play a part in con- 

 4 



